1. Technical Field of the Invention
The present invention relates to a mobile telecommunications network and, in particular, to a subscriber feature for automatically establishing a call conference within a home zone.
2. Description of Related Art
With the introduction of the Global System for Mobile (GSM) communication and the Personal Communications System (PCS), the concept of wireline telephone service and wireless telephone service has changed drastically. Instead of assigning a telephone number for a particular geographic location, in accordance with the GSM or PCS, a telephone number is assigned towards a particular subscriber. For example, instead of having a single telephone number and line to a house, each member of the household has a separate telephone number and telephone service. As a result, each subscriber is associated with a Subscriber Identity Module (SIM) card. Using an SIM card, a mobile subscriber is able to store necessary mobile subscriber information in a detachable memory unit and freely associate it with any available mobile station. Such information includes a mobile subscriber's Mobile Station Integrated Service Digital Network (MSISDN) number, International Mobile Subscriber Identity (IMSI) number, or other user specified information, such as preferred speed dialing lists or screening lists. By inserting a mobile subscriber's SIM card into a mobile station, the stored subscriber information in the inserted SIM card is available to the mobile subscriber's new terminal. As a result, the mobile subscriber is able to freely utilize any available mobile station while maintaining the same MSISDN number and subscriber feature data.
Furthermore, in order to enable the mobile subscriber to utilize the mobile station as a cordless phone while traveling within a certain geographic location, the concept of "home zone" has been introduced. If the mobile subscriber makes a call within his home zone, the mobile station functions as a conventional cordless phone and the mobile subscriber is not charged for the air time, or is charged at a significantly lower air time rate. Accordingly, within his home zone, the mobile subscriber can utilize his mobile station to originate outgoing calls without incurring expensive air time charges and without physically using a different telephone terminal, e.g., wireline terminal such as a cordless phone.
With conventional wireline telecommunications networks, a number of telephone terminals are often connected to a single telephone line. Consequently, whenever a subscriber is in speech using one of the connected terminals, other members of the same household can easily join in on the conversation by picking up a handset from other available terminals. Therefore, without requiring any sophisticated conferencing circuits or devices, three subscribers can simultaneously speak with each other. On the other hand, within mobile telecommunications networks, in order for more than two mobile subscribers to communicate with each other, three way calling or other call conferencing features must be utilized. For example, a first mobile subscriber in speech connection with a second mobile subscriber must place the second mobile subscriber on call hold and originate an outgoing call towards a third mobile subscriber. After the new outgoing call connection towards the third mobile subscriber has been established, the first mobile subscriber has to connect all the subscribers together by utilizing a call conferencing subscriber feature such as three way calling. As a result, unlike conventional wireline terminals, a mobile subscriber in the same household cannot merely walk over to another terminal in the next room, simply pick up the handset, and conveniently participate in the existing mobile conversation.
Accordingly, in a manner similar to conferencing conventional wireline terminals, there is a need for a mechanism to enable a mobile subscriber to conveniently and economically connect to an existing mobile call connection.